Investigation of the urinary sodium-to-potassium ratio target level based on the recommended dietary intake goals for the Japanese population: The INTERMAP Japan

Effects of monitoring dietary biomarkers and providing vegetable juice on metabolic syndrome components in adults with an overweight or obese body mass index in Ulaanbaatar: a randomized controlled trial

BACKGROUND

Mongolian people have traditionally had poor vegetable intake habits, which is a cause of increasing prevalence of metabolic syndrome. Monitoring vegetable intake through the dietary biomarkers such as skin carotenoid level, and urinary sodium-to-potassium (Na/K) ratio (represents intake status of salt and vegetable), has been recently suggested to be useful to improve dietary habits. Vegetable juices are an easy way to consume vegetable-derived ingredients. This study aimed to examine the following two points in adults with an overweight or obese body mass index (BMI) in Ulaanbaatar; (1) relationships between these dietary biomarkers and metabolic syndrome components, and (2) effects of an intervention combining regular monitoring of these dietary biomarkers and provision of vegetable juices on values of the dietary biomarkers and metabolic syndrome components.

METHODS

Ninety-four Mongolian adults with BMI ≥ 25 living in Ulaanbaatar were analyzed. (1) Relationships between baseline values of dietary biomarkers and metabolic syndrome components were analyzed by simple correlation and multiple regression analyses. (2) Participants were randomly allocated to control, monitoring, and monitoring + vegetable juice groups. During the 8-week intervention, the monitoring and monitoring + vegetable juice groups were monitored their dietary biomarkers and blood pressure every two weeks, and the monitoring + vegetable juice group was additionally provided with vegetable juice every day. Changes in dietary biomarkers and metabolic syndrome components before and after intervention were compared among the three groups.

RESULTS

(1) The skin carotenoid levels were negatively correlated with blood triglyceride levels, whereas the urinary Na/K ratio was positively associated with systolic and diastolic blood pressure. (2) Through the intervention, the monitoring + vegetable juice group showed significant increase in skin carotenoid level (+ 1.72), decrease in urinary Na/K ratio (- 0.80 mol/mol), and decrease in waist circumference (- 2.63 cm) compared to the control group (+ 0.28, + 0.45, and + 0.22, respectively).

CONCLUSIONS

The combination of the monitoring dietary biomarkers and providing vegetable juice was suggested to be effective in improving dietary habits and metabolic syndrome components including waist circumference in Mongolian adults with an overweight or obese BMI.

TRIAL REGISTRATION

UMIN-CTR Clinical Trial UMIN000051715 on July 26, 2023.

Role of dietary potassium and salt substitution in the prevention and management of hypertension

Cardiovascular diseases (CVD) continue to be the leading cause of deaths and disability worldwide and the major contributor is hypertension. Despite all the improvements in detecting hypertension together with technological advances and affordable, efficacious and relatively free of adverse effects anti-hypertensive agents, we continue to struggle to prevent the onset of hypertension and to control blood pressure (BP) to acceptable targets. The poor control of hypertension is commonly due to non-adherence to medications. Another reason is the failure to adopt diet and lifestyle changes. Reduction of dietary salt intake is important for lowering BP but the role of potassium intake is also important. Globally the intake of sodium is double that of the recommended 2 gm per day (equivalent to 5 gm of sodium chloride/salt) and half that of the daily recommended intake of potassium of 3500 mg/day, giving a sodium-to-potassium ratio of >1, when ideally it should be <1. Many studies have shown that a higher potassium intake is associated with lower BPs, particularly when coupled concurrently with a lower sodium intake giving a lower sodium to potassium ratio. Most hypertension guidelines, while recommending reduction of salt intake to a set target, do not specifically recommend a target for potassium intake nor potassium supplementation. Here we review the role of potassium and salt substitution with potassium in the management of hypertension. Hence, the focus of dietary changes to lower BP and improve BP control should not be on reduction of salt intake alone but more importantly should include an increase in potassium intake.

Practical use and target value of urine sodium-to-potassium ratio in assessment of hypertension risk for Japanese: Consensus Statement by the Japanese Society of Hypertension Working Group on Urine Sodium-to-Potassium Ratio

Epidemiological studies have demonstrated that the urine sodium-to-potassium (Na/K) ratio is more positively associated with high blood pressure and cardiovascular disease risk than either urine sodium or potassium excretion alone. In this consensus statement, we recommend using the average Na/K ratio of casual urines randomly taken in various times on at least four days a week for a reliable individual estimate because of high day-to-day and intraday variability of casual urine Na/K ratio within individuals. Although a continuous positive association exists between the Na/K ratio and high blood pressure or cardiovascular disease risk, for clinical and public health decision making for Japanese, we recommend using an average urine Na/K ratio of 2 as an optimal target value because this aligns with recommendations for both sodium and potassium intake in the Dietary Reference Intakes for Japanese, 2020, considering a typical Japanese dietary pattern. We also suggest that an average urine Na/K ratio of 4 is a feasible target value to achieve a temporary goal of being below the mean values of the urine Na/K ratio across Japanese general populations. These recommendations apply mainly for apparently healthy individuals, but not for patients with specific conditions due to the lack of supporting data. Current evidence for the usefulness of measuring the urine Na/K ratio for the prevention or control of hypertension remains inconclusive and warrants further investigation.

Urinary Biomarkers in Screening for the Usual Intake of Fruit and Vegetables, and Sodium, Potassium, and the Sodium-to-Potassium Ratio: Required Number and Accuracy of Measurements

Because of within-individual variation, surveys to estimate an individual's usual food intake must be conducted over many days, in general. Here, using non-invasive biomarkers, we examined the number of measurements required to screen for the usual intake of fruit and vegetables, in addition to sodium, potassium, and the sodium-to-potassium (Na/K) ratio. Participants were 202 subjects aged 40-74 years from five areas of Japan who completed weighed food records (WFR) and five 24-hour urinary collections (24-h UCs) between 2012 and 2013. The number of 24-h UCs required to screen for intake that deviated from guidelines estimated by the WFR and their accuracies were assessed by the area under the curve (AUC) in a receiver-operating characteristics (ROC) analysis. The single urinary excretion of sodium, potassium, and the Na/K ratio showed moderate performance (AUC value: >0.7) in discriminating deviations from their criteria by respective intake based on the WFR. Urinary potassium excretion also showed moderate performance (AUC value: >0.7) in estimating the intake of vegetables but could not be used to estimate fruit intake even after five collections. The non-invasive measurement of biomarkers in a single 24-h UC showed moderate performance in screening the usual intake of vegetables, as measured based on the 12-day WFR, as well as of sodium, potassium, and the Na/K ratio.

Association between sodium-to-potassium ratio in spot urine and hospitalization due to heart failure in high-risk Japanese patients

Background

In Japanese cardiovascular (CV) high-risk patients, the ESPRIT (Evaluation of Sodium Intake for the Prediction of Cardiovascular Events in Japanese High-risk Patients) study showed that high sodium excretion (≥4.0 g/day) was associated with a composite CV events of heart failure (HF) hospitalization, acute coronary syndrome, cerebrovascular events, and CV deaths. In this context, the sodium-to-creatinine (Na/Cr) ratio in spot urine was found to be significantly associated with HF hospitalizations. Since a stable potassium balance plays a particularly relevant role for CV patients, this post-hoc study was designed to investigate the extent to which consideration of the sodium-to-potassium (Na/K) ratio represents a better predictor of HF hospitalizations in the ESPRIT study population.

Methods

This is a post-hoc analysis of a previously reported ESPRIT study (n = 520, 60 HF hospitalizations).

Results

Receiver operating curve analysis yielded optimal Na/K ratio cut-off value of 2.9 for detecting HF hospitalization. Kaplan-Meier curve showed that high Na/K ratio in spot urine was associated with increased HF hospitalization (p < 0.001). Cox proportional hazards model analysis revealed that high Na/K ratio was associated with HF hospitalization with a hazard ratio of 2.97 (confidence interval: 1.67-5.61). An association between high Na/K ratio and HF hospitalization remained after adjustments for Na/Cr ratio in spot urine or the use of diuretics.

Conclusion

The Na/K ratio in spot urine is associated with HF hospitalization in high-risk Japanese patients.

Low urinary sodium-to-potassium ratio in the early phase following single-unit cord blood transplantation is a predictive factor for poor non-relapse mortality in adults

Although daily higher urinary sodium (Na) and potassium (K) excretion ratio is associated with the risk of cardiovascular disease in the general population, a low Na/K ratio is associated with renal dysfunction in critically ill patients. Thus, we retrospectively analyzed the impact of daily urinary Na and K excretion and their ratio on non-relapse mortality (NRM) and overall mortality in 172 adult single-unit cord blood transplantation (CBT) patients treated at our institution between 2007 and 2020. Multivariate analysis showed that a low urinary Na/K ratio at both 14 days (hazard ratio [HR], 4.82; 95% confidence interval [CI], 1.81-12.83; P = 0.001) and 28 days (HR, 4.47; 95% CI 1.32-15.12; P = 0.015) was significantly associated with higher NRM. Furthermore, a low urinary Na/K ratio at 28 days was significantly associated with higher overall mortality (HR, 2.38; 95% CI 1.15-4.91; P = 0.018). Patients with a low urinary Na/K ratio had decreased urine volume, more weight gain, experienced more grade III-IV acute graft-versus-host disease, and required corticosteroids by 28 days after CBT. These findings indicate that a low urinary Na/K ratio early after single-unit CBT is associated with poor NRM and survival in adults.

Regional variation in pre-dialysis blood pressure and its association with cardiovascular mortality rates in Japanese patients undergoing dialysis

Adequate blood pressure (BP) management poses a significant challenge in improving the prognosis of patients undergoing dialysis. We aimed to investigate the relationship between pre-dialysis systolic blood pressure (SBP) and underlying disease in Japanese patients undergoing dialysis, based on prefectural location, and assess the association between pre-dialysis SBP and cardiovascular disease (CVD) mortality rate. We extracted the basic information of 336,182 patients who were undergoing dialysis in 2021 from the Web-based Analysis of Dialysis Data Archives database. Data on average pre-dialysis SBP were analyzed according to sex, prefectural location, and diabetic status, and the CVD mortality rate for each prefecture was calculated. The mean pre-dialysis SBP of the patients (males, 66.3%; mean age, 69.7 ± 12.5 years) was 151.9 ± 24.7 mmHg. Overall, 133,037 patients had underlying diabetic kidney disease (DKD). The patients with DKD were younger, had a shorter dialysis duration, and a higher pre-dialysis SBP than those with non-DKD comorbidities. The prefecture-based mean pre-dialysis SBP values were all higher than 140 mmHg. At the prefectural level, CVD mortality rate was positively correlated with pre-dialysis SBP (r = 0.3127, p = 0.0324) and diastolic blood pressure (r = 0.3378, p = 0.0202) among female patients. At the prefectural level, pre-dialysis SBP is >140 mmHg in Japanese patients undergoing dialysis, especially in those with DKD. The positive association between pre-dialysis SBP and CVD mortality rate suggests that optimal BP management at the prefectural level may reduce CVD mortality rates. At the prefectural level, pre-dialysis SBP is higher than 140 mmHg in Japanese patients undergoing dialysis, especially higher in those with DKD.

2023 update and perspectives

Total 276 manuscripts were published in Hypertension Research in 2022. Here our editorial members picked up the excellent papers, summarized the current topics from the published papers and discussed future perspectives in the sixteen fields. We hope you enjoy our special feature, 2023 update and perspectives in Hypertension Research.